Reducing sleeve, modular system for providing a reducing sleeve assembly, and machining assembly

ABSTRACT

A reducing sleeve for fastening a machining tool in a tool holder is described. The reducing sleeve includes a reducing sleeve body, which has a first tool-side end and a second tool holder-side end. In addition, at least one coolant supply channel is provided in the reducing sleeve body. In one embodiment, a safety unit with a pull-out safety geometry has a sealing element, such as an O-ring, to selectively direct coolant through coolant holes in the safety unit and the at least one coolant supply channel or alternatively through a central coolant channel. In this embodiment, a multifunctional interface, and additional O-ring and a sealing unit are not required. A modular reducing sleeve assembly includes a reducing sleeve and a safety unit as separate parts. In addition, a machining assembly including a tool holder, a reducing sleeve, and a machining tool is described.

CLAIM TO PRIORITY

This application is a continuation-in-part of application Ser. No.17/225,499, filed on Apr. 8, 2021, which in turn claims prioritypursuant to 35 U.S.C. § 119(a) to German Patent Application Number102020109775.1, filed Apr. 8, 2020, which is incorporated herein byreference in its entirety.

FIELD

The invention relates to a reducing sleeve for fastening a machiningtool in a tool holder. The reducing sleeve comprises a reducing sleevebody which extends along a reducing sleeve center axis and which has afirst end, which is a tool-side end in the clamped state of the reducingsleeve, and a second end, which is opposite to the first end and is atool holder-side end in the clamped state of the reducing sleeve. Inaddition, the reducing sleeve body comprises at least one coolant supplychannel extending at a distance from the reducing sleeve center axis.

The invention furthermore relates to a modular system for providing areducing sleeve assembly.

The invention also relates to a machining assembly with a tool holder, areducing sleeve of the aforementioned type arranged in the tool holder,and a machining tool with a tool shaft, which is accommodated in theinterior of the reducing sleeve.

BACKGROUND

Such reducing sleeves and the machining assemblies equipped with themare known from the prior art. The tool holders can be hydraulicallyactuatable tool holders, which are also referred to as hydraulic toolholders in short.

A reducing sleeve usually serves to reliably hold a machining tool in anassociated tool holder of a machining assembly. This is essentially doneby clamping a tool shaft via the reducing sleeve in the tool holder. Thereducing sleeve bridges the differences in diameter or thickness betweenthe machining tool and the tool holder. In this connection, reducingsleeves can be designed according to numerous variants. Known are inparticular reducing sleeves which have an additional pull-out safetygeometry so that the tool shaft can be clamped in the tool holder on theone hand and on the other hand is secured via the pull-out safetygeometry in a form-fitting manner against being pulled out of thereducing sleeve and/or the tool holder. Such reducing sleeves are alsoknown under the term “safe lock” so that a safe lock mechanism or safelock reducing sleeves are also often mentioned.

A coolant supply channel in the reducing sleeve body can be used toconduct coolant to a machining zone. For this purpose, it is notnecessary that coolant supply channels are also provided on themachining tool itself. The reducing sleeve can therefore also serve tosupply the coolant. Of course, reducing sleeves without coolant supplychannels are also known in this connection. These sleeves can be used,for example, together with machining tools in which coolant supplychannels are integrated.

In summary, numerous variants of reducing sleeves are known. Dependingon the machining task to be performed, the most suitable one can beselected from these variants. However, this results in a certain amountof costs for storage, which has the goal of always being able to keepthe appropriate reducing sleeve available for a certain spectrum ofmachining tasks.

This applies on the one hand to manufacturing environments in which thereducing sleeve and the machining tools held by means of it are used toproduce other components. On the other hand, this also applies to amanufacturing environment in which reducing sleeves are produced in highvariance. In both manufacturing environments, known reducing sleevesthus cause costs that result from the large number of variants mentionedand the associated storage.

SUMMARY

The object of the invention is to improve known reducing sleeves so thatthey can be produced cost-effectively and cause low costs when used toproduce other components.

The object is achieved by a reducing sleeve of the type mentioned at thebeginning, which at the second end has a multifunctional interface whichis designed both for coupling the reducing sleeve body to a sealing unitfor sealing the at least one coolant supply channel and for coupling thereducing sleeve body to a safety unit for providing a pull-out safetygeometry for the machining tool. The reducing sleeve can thus be useduniversally in various applications.

The reducing sleeve can in particular be used without a sealing unit andwithout a safety unit. It can then serve to hold machining tools that donot have any coolant supply channels. A coolant supply of an associatedmachining zone then takes place via the coolant supply channels providedon the reducing sleeve. If the reducing sleeve is equipped with a safetyunit, pull-out safety of the machining tool that goes beyond mereclamping can be provided. In the event that the reducing sleeve isequipped with a sealing unit, the coolant supply channels provided inthe reducing sleeve are reliably sealed. Thus, either a machining taskcan be reliably fulfilled in dry processing or coolant can be introducedinto such coolant supply channels that are provided on the machiningtool.

The provision of such a reducing sleeve together with a sealing unit anda safety unit causes significantly reduced storage costs in comparisonto known solutions because instead of various reducing sleeves, only asingle reducing sleeve according to the invention must be kept availabletogether with the safety unit and/or the sealing unit. The safety unitand the sealing unit act as adapters in the broadest sense. In addition,the reducing sleeve according to the invention can be a component of amodular system, which is explained below.

The reducing sleeve body of such a reducing sleeve is in particular ageneratively manufactured component, which is also referred to as anadditively manufactured component. It is preferably produced by means ofa 3D printing method or an SLS method (“selective laser sintering”).Alternatively, the reducing sleeve body is produced conventionally, inparticular using machining manufacturing methods.

In one variant, the reducing sleeve is provided at its tool-side endwith a contact flange, via which it can be attached to an associatedtool holder. This makes it possible to reliably and precisely positionthe reducing sleeve on the tool holder.

It is also possible for a slot to extend on the reducing sleeve body(substantially) in parallel to the reducing sleeve center axis. In thisway, the elasticity of the reducing sleeve can be increased in thecircumferential direction. This increases the reliability with which thereducing sleeve can clamp a machining tool.

The multifunctional interface basically ensures that several differentfunctions (multifunctionality) can be covered by means of the interfaceby coupling corresponding components, e.g., the sealing unit or thesafety unit, to the multifunctional interface.

The at least one coolant supply channel can at least in sections extendin the interior of the reducing sleeve body or at least in sections bedesigned as a groove that extends on an outer circumference of thereducing sleeve body. In the first case, the coolant supply channel isthus embedded at least in sections in the reducing sleeve body in such away that it is circumferentially closed. In the second case, the coolantsupply channel is radially open at least in sections and is completed,i.e., closed, by an associated wall of the tool holder. Both variantsmake it possible to reliably introduce coolant into a machining zone orto conduct it to the machining zone.

According to one embodiment, the interface comprises an internal thread,wherein the internal thread is designed to cooperate both with acounterpart of the sealing unit and with a counterpart of the safetyunit. The internal thread is thus a core component of themultifunctional interface. It is designed to cooperate with a pluralityof components acting as adapters, in particular with the safety unit andthe sealing unit. This results in a wide range of possible uses of thereducing sleeve. In addition, the multifunctional interface can be usedfor adapters to be developed in the future.

The internal thread can act as a latching contour for the counterpart ofthe sealing unit. The internal thread thus has at least two functions.On the one hand, it acts as a thread and on the other hand as a latchingcontour. This results in a possible multifunctional use of theinterface.

In principle, a reducing sleeve assembly can also be provided, whichcomprises a reducing sleeve of the aforementioned type as well as asealing unit for sealing the at least one coolant supply channel of thereducing sleeve and/or a safety unit for providing a pull-out safetygeometry for the machining tool.

In addition, the object is achieved by a modular system for providing areducing sleeve assembly. This modular system comprises a reducingsleeve according to the invention, a sealing unit for sealing the atleast one coolant supply channel of the reducing sleeve, and a safetyunit for providing a pull-out safety geometry for the machining tool.The multifunctional interface of the reducing sleeve can be selectivelycoupled to the sealing unit or the safety unit. In comparison to theprior art, in which a plurality of different reducing sleeves must beprovided, such a modular system causes significantly reduced storagecosts with unchanged functional scope. As a result, only comparativelylow manufacturing and provision costs are caused. This is in particulardue to the fact that the safety unit and the sealing unit aresignificantly smaller than the reducing sleeve. In addition, the safetyunit and the sealing unit are designed to cooperate with variousreducing sleeves. This also reduces the storage costs and consequentlythe manufacturing and provision costs.

By means of such a modular system, a reducing sleeve assembly can thusbe provided, which fulfills the same function as a known reducing sleevewithout coolant supply channels, which can, for example, be used formachining tools which are equipped with coolant supply channels. In thiscase, the reducing sleeve according to the invention is provided withthe sealing unit. In addition, a reducing sleeve assembly which hascoolant supply channels can be provided by means of the modular system.This reducing sleeve assembly can cooperate with machining tools that donot have their own coolant supply channels. In this case, the reducingsleeve according to the invention is equipped neither with the sealingunit nor with the safety unit. Moreover, a reducing sleeve assemblywhich is provided with a pull-out safety geometry (safe lock) can beprovided by means of the modular system. This reducing sleeve assemblycan be used with such machining tools that have a corresponding countergeometry for the pull-out safety geometry. In this application, thereducing sleeve according to the invention is equipped with the safetyunit.

In this connection, the sealing unit is preferably a plastic part. Thesealing unit is designed as an injection-molded part, for example.

The safety unit can be designed as a generatively/additivelymanufactured component. The safety unit is then preferably produced bymeans of a 3D printing method or an SLS method.

According to one variant, the safety unit is coupled to the reducingsleeve body via the multifunctional interface. In this case, a firstexternal thread of the safety unit is in particular screwed into theinternal thread of the interface. The safety unit is a separatecomponent from the reducing sleeve body. It is reliably connected to thereducing sleeve body via the external thread and the internal thread.The external thread represents a counterpart for the internal thread ofthe multifunctional interface. The designation of the external threadfirst serves only as a simple explanation. This does not imply a numberof external threads. Such a reducing sleeve assembly can thereforeprovide an additional pull-out safety of a machining tool (safe lock) inaddition to the usual clamping.

The safety unit can have a central opening to the coolant supply. It canthus also be used in connection with machining tools which have theirown coolant supply channels.

In this connection, the safety unit preferably has a pull-out safetygeometry, which is designed to form, with a machining tool, a form fitwhich acts along the reducing sleeve center axis and prevents themachining tool from being pulled out of the reducing sleeve. In thiscase, the pull-out safety geometry is in particular located radiallywithin the first external thread. The pull-out safety geometrypreferably extends spirally on an inner circumference of the safetyunit. According to one embodiment, the pull-out safety geometry thusrepresents a threaded section into which the machining tool, moreprecisely an associated tool shaft, can be screwed.

The safety unit can comprise a second external thread, which serves tofasten a composite of the safety unit and of the reducing sleeve to thetool holder. The second external thread is preferably arranged axiallyadjacent to the first external thread, in particular in relation to thereducing sleeve center axis. The diameter of the first external threadfurther preferably differs from the diameter of the second externalthread. In particular, the diameter of the second external thread issmaller than the diameter of the first external thread. The safety unitcan thus be mounted only in a single position on the reducing sleeve.Incorrect assembly is therefore reliably excluded (“poka-yoke”principle). The machining tool can also be held particularly reliably onthe tool holder in this way.

Alternatively, the sealing unit is coupled via the multifunctionalinterface to the reducing sleeve body. In particular, a latching contourof the sealing unit is latched to the internal thread of the interface.The latching contour of the sealing unit represents a counterpart forthe internal thread of the multifunctional interface. The sealing unitis also a separate component from the reducing sleeve body. As alreadyexplained in connection with the safety unit, the sealing unit can alsohave a central opening to the coolant supply. Machining tools thatthemselves have coolant supply channels can then also be used incombination with the sealing unit.

The sealing unit advantageously comprises a substantially (circular)cylindrical latching section, the center axis of which substantiallycoincides with the reducing sleeve center axis in the assembled state ofthe sealing unit, wherein the latching contour of the sealing unit isarranged on an outer circumference of the latching section. In this way,the sealing unit can be reliably latched to the reducing sleeve.

Alternatively, or additionally, the sealing unit comprises a sealingsection for the fluid-tight sealing of the at least one coolant supplychannel. In the assembled state of the sealing unit, the sealing sectionin particular seals the at least one coolant supply channel in the axialdirection. The coolant supply channel or channels of the reducing sleeveis or are thus reliably sealed. Overall, a simple design of the sealingunit results so that it can be produced easily and cost-effectively.

The sealing unit is preferably made of a plastic. On the one hand, thisresults in advantageous sealing properties. On the other hand, such asealing unit can be produced easily and cost-effectively, in particularin high quantities.

In addition, the object is achieved by a machining assembly of the typementioned at the beginning, in whose tool holder a reducing sleeveaccording to the invention is arranged. The tool shaft is accommodatedin the interior of the reducing sleeve according to the invention. Thecoolant supply channel in the reducing sleeve is optionally coupled in afluid-conducting manner to an associated coolant supply channel in thetool holder so that a machining zone can be supplied with coolant.

The reducing sleeve can be equipped with a safety unit, wherein themachining tool is coupled to the safety unit via a form fit which actsalong the reducing sleeve center axis and counteracts any pulling of themachining tool out of the reducing sleeve. In this case, the reducingsleeve is in particular additionally axially fastened via the safetyunit in the tool holder. This results in a particularly reliable hold ofthe machining tool in the tool holder.

Alternatively, the reducing sleeve can be equipped with a sealing unit,by means of which all coolant supply channels provided on the reducingsleeve are sealed. Then, either a coolant supply channel in themachining tool can be supplied with coolant via the tool holder or acoolant supply can be dispensed with so that dry processing is possible.

In one embodiment, a modular reducing sleeve assembly comprises areducing sleeve and a safety unit. The reducing sleeve comprises areducing sleeve body extending along a reducing sleeve center axis, thereducing sleeve body having a first end, which is a tool-side end in theclamped state of the reducing sleeve, and a second end opposite to thefirst end and is a tool holder-side end in the clamped state of thereducing sleeve. The reducing sleeve body comprises at least one coolantsupply channel extending at a distance from the reducing sleeve centeraxis, the reducing sleeve body further comprising a central coolantsupply channel. The safety unit is mounted on the second end of thereducing sleeve. The safety unit has a pull-out safety geometry and aplurality of coolant holes in fluid communication with the at least onecoolant supply channel of the reducing sleeve. Coolant is directed to amachining tool only through the central coolant supply channel of thesafety unit when a sealing element is mounted on the safety unit, andcoolant is directed through the plurality of coolant holes of the safetyunit and the at least one coolant supply channel of the reducing sleevewhen the sealing element is not mounted on the safety unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained below with reference to various exemplaryembodiments that are shown in the accompanying drawings. The drawingsshow:

FIG. 1 is an exploded view of a machining assembly according to theinvention according to a first embodiment with a reducing sleeveassembly provided by a modular system according to the invention andcomprising a reducing sleeve according to the invention,

FIG. 2 is an illustration, corresponding to FIG. 1 , of the machiningassembly according to the first embodiment, wherein the reducing sleeveassembly is shown in a sectional view,

FIG. 3 is a perspective illustration of a reducing sleeve designedaccording to one variant,

FIG. 4 is another perspective illustration of the reducing sleeve ofFIG. 3 ,

FIG. 5 is a side view of the reducing sleeve of FIGS. 3 and 4 ,

FIG. 6 is a sectional view of the reducing sleeve of FIG. 5 along theline VI-VI,

FIG. 7 is an exploded view of a machining assembly according to theinvention according to a second embodiment with a reducing sleeveassembly provided by a modular system according to the invention andcomprising a reducing sleeve according to the invention,

FIG. 8 is an illustration, corresponding to FIG. 7 , of the machiningassembly according to the second embodiment, wherein the reducing sleeveassembly is assembled and shown in a sectional view,

FIG. 9 is an exploded view of a machining assembly according to theinvention according to a third embodiment with a reducing sleeveassembly provided by a modular system according to the invention andcomprising a reducing sleeve according to the invention,

FIG. 10 is an illustration, corresponding to FIG. 9 , of the machiningassembly according to the third embodiment, wherein the reducing sleeveassembly is assembled and shown in a sectional view,

FIG. 11 is an isolated, perspective illustration of a sealing unit ofthe machining assembly according to the invention of FIGS. 7 and 8 ,

FIG. 12 is an isolated, perspective illustration of a safety unit of themachining assembly according to the invention of FIGS. 9 and 10 ,

FIG. 13 is the safety unit of FIG. 12 from a different perspective,

FIG. 14 is a perspective view of a reducing sleeve according to anotherembodiment,

FIG. 15 is a cross-sectional view of the reducing sleeve of FIG. 14 ,

FIG. 16 is an enlarged view of the coolant exits proximate the first endof the reducing sleeve of FIG. 14 ,

FIG. 17 is a perspective view of the reducing sleeve of FIG. 14 inphantom,

FIG. 18 is an enlarged view of the header section and outlet nozzles,

FIG. 19 is a rear perspective view of a safety unit according to anotherembodiment,

FIG. 20 is a front perspective view of the safety unit of FIG. 19 ,

FIG. 21 is a rear view of the safety unit of FIG. 19 ,

FIG. 22 is a front view of the safety unit of FIG. 19 ,

FIG. 23 is a cross-sectional view of the safety unit taken along line23-23 of FIG. 21 ,

FIG. 24 is a cross-sectional view illustrating the coolant path throughof a reducing sleeving assembly when the sealing element is not mountedon the safety unit of FIG. 19 , and

FIG. 25 is a cross-sectional view illustrating the coolant path throughthe reducing sleeving assembly when the sealing element is mounted onthe safety unit of FIG. 19 .

DETAILED DESCRIPTION

FIGS. 1 and 2 show a machining assembly 10 according to a firstembodiment.

It comprises a tool holder 12, which is designed as a hydraulic toolholder.

The machining assembly 10 furthermore has a reducing sleeve assembly 13with a reducing sleeve 14, which is arranged in the tool holder 12 inthe assembled state.

In addition, the machining assembly 10 comprises a machining tool 16having a tool shaft 18. In the assembled state, the tool shaft 18 isaccommodated in the interior of the reducing sleeve 14.

The reducing sleeve 14 thus serves to fasten the machining tool 16 inthe tool holder 12.

For this purpose, it comprises a reducing sleeve body 20, which extendsalong a reducing sleeve center axis 22.

Said reducing sleeve body has a first end 24 and a second end 26, whichis opposite to the first end 24. In this case, in the clamped state ofthe reducing sleeve 14, the first end 24 is a tool-side end, via whichthe machining tool 16 is inserted into the reducing sleeve 14, and thesecond end 26 is a tool holder-side end, via which the reducing sleeve14 is inserted into the tool holder 12.

At the first end 24, the reducing sleeve 14 additionally has a contactflange 28, which abuts against the tool holder 12 in the assembled stateaxially, i.e., in relation to the reducing sleeve center axis 22.

The reducing sleeve body 20 also has at least one optional,substantially axially extending slot 20 a, which serves to increase thecircumferential elasticity.

A holding region 30 for the tool shaft 18 is moreover formed in theinterior of the reducing sleeve body 20. In the assembled state, thetool shaft 18 is clamped in the holding region 30 by means of thehydraulic tool holder 12.

Furthermore, the reducing sleeve body 20 has a plurality of coolantsupply channels 32, each of which is composed of a first bore section 32a, which extends substantially in parallel to the reducing sleeve centeraxis 22, a second bore section 32 b, which extends substantiallyradially with respect to the reducing sleeve center axis 22, a groovesection 32 c, and a third bore section 32 d.

Since the groove section 32 c is by far the largest section of thecoolant supply channel 32, the coolant supply channel 32 can simply alsobe referred to as a groove 32 e.

The at least one groove 32 e can be formed on the outside of thereducing sleeve body 20 so that the at least one coolant supply channel32 is open to the radial outside. When inserting the reducing sleeve 14into the tool holder 12, the corresponding groove 32 e is closed by theinner side of the tool holder 12 so that the at least one(circumferentially closed) coolant supply channel 32 forms.

Alternatively, the at least one coolant supply channel 32 can beembedded in the reducing sleeve body 20. In this respect, the respectivecoolant supply channel 32 can already be closed circumferentially.

A machining zone that is not shown in greater detail can be suppliedwith coolant by means of the coolant supply channels 32.

The coolant supply channels 32 all extend at a distance from thereducing sleeve center axis 22, i.e., radially to the reducing sleevecenter axis 22. Furthermore, the coolant supply channels 32 extendsubstantially axially, i.e., in parallel to the reducing sleeve centeraxis 22.

In this connection, the machining tool 16 is designed without its owncoolant supply channels.

In addition, the reducing sleeve 14 is equipped with a multifunctionalinterface 34, which is explained in more detail in connection with thefollowing embodiments.

FIGS. 3 to 6 show a variant of the reducing sleeve 14. Only thedifferences to the reducing sleeve according to FIGS. 1 and 2 arediscussed below.

The reducing sleeve 14 according to the variant differs from thepreviously explained reducing sleeve 14 by the shape of the coolantsupply channels 32.

A circumferential coolant supply groove 32 f is provided on the outercircumference of the reducing sleeve body 20. Coolants can be introducedinto said coolant supply groove via coolant supply channels (not shownin greater detail) of the associated tool holder 12.

Several coolant supply slots 32 g extend from the coolant supply groove32 f along the reducing sleeve center axis 22. The coolant supply slotsare continuous in the radial direction on the reducing sleeve body 20and are sealed radially on the inside by inserting a tool shaft 18 intothe reducing sleeve body 20 and radially on the outside by inserting thereducing sleeve 14 into the tool holder 12.

In the region of the first end 24, each coolant supply slot 32 g isadjoined by a bore section 32 h which extends substantially in parallelto the reducing sleeve center axis 22 and via which coolant can beintroduced into a machining zone not shown in greater detail.

In the event that the coolant supply channels 32 of the reducing sleeve14 are not to be used for coolant supply, a sealing element, e.g., anO-ring 33 a, can be inserted into the coolant supply groove 32 f so thatthe coolant supply slots 32 g are sealed in a fluid-tight manner withrespect to a coolant supply on the tool holder side (see FIG. 6 ).

In this connection, a machining tool 16 having its own cooling channelscan be accommodated in the reducing sleeve 14, for example.

In addition, independently of the use of the coolant supply channels 32,an O-ring 33 b can be provided, which is located in a sealing mannerbetween the contact flange 28 and the tool holder 12 in the assembledstate of the reducing sleeve. The O-ring 33 b ensures that coolant exitsexclusively via the provided coolant supply channels 32 and not somewhatvia any intermediate space formed between the reducing sleeve 14 and thetool holder 12.

It goes without saying that the O-ring 33 b can also be used in thereducing sleeve 14 of FIGS. 1 and 2 .

FIGS. 7 and 8 show a machining assembly 10 according to a secondembodiment. Only the differences to the first embodiment are discussedbelow. As for the rest, reference is made to the explanations above.

The reducing sleeve 14 is now equipped with a sealing unit 36, by meansof which all coolant supply channels 32 provided on the reducing sleeve14 are sealed.

The sealing unit 36 has a sealing section 38 for the fluid-tight sealingof the coolant supply channels 32. In the assembled state of the sealingunit 36, said sealing section in particular seals the coolant supplychannels 32 in the axial direction, i.e., along the reducing sleevecenter axis 22.

In addition, the sealing unit 36 has a substantially cylindricallatching section 40.

In the assembled state of the sealing unit 36, a center axis of thelatching section 40 substantially coincides with the reducing sleevecenter axis 22.

On an outer circumference of the latching section 40, a latching contour42 can also be provided, which is formed by a knurling or corrugation inthe embodiment shown.

The sealing unit 36 is preferably made of a plastic.

The sealing unit 36 is coupled via the multifunctional interface 34 tothe reducing sleeve body 20.

For this purpose, the interface 34 comprises an internal thread 44 (seealso FIG. 2 ), which is designed to cooperate with the latching section40 of the sealing unit 36, which acts as a counterpart for this purpose.

The internal thread 44 thus simultaneously represents a latching contour46 of the reducing sleeve 14.

In other words, the sealing unit 36 is latched to the reducing sleevebody 20.

The sealing unit 36 can be seen in detail in FIG. 11 .

FIGS. 9 and 10 show a machining assembly 10 according to a thirdembodiment. Only the differences to the already explained embodimentsare again discussed. As for the rest, reference is made to theexplanations above.

Instead of the sealing unit 36, a safety unit 48 is now coupled via themultifunctional interface 34 to the reducing sleeve body 20.

In this connection, the safety unit 48 comprises a first external thread50, which is screwed into the internal thread 44 of the interface in theassembled state. The safety unit 48 is thereby fixedly connected to thereducing sleeve body 20. In particular, this applies along the reducingsleeve center axis 22.

At an axial end of the safety unit 48, which faces the holding region 30in the assembled state, a chamfer 48 a is also provided, the chamfersurface of which corresponds to a conical lateral surface section.

In the assembled state of the safety unit 48, the chamfer 48 a abutsagainst a stop surface 48 b, which is formed on the reducing sleeve body20 (see also FIGS. 2 and 6 ). The stop surface 48 b is also designed asa conical lateral surface section so that the chamfer 48 a can abut flatagainst it.

This results in a precise alignment of the safety unit 48 with respectto the reducing sleeve 14. This relates in particular to the coaxialnature of a center axis of the safety unit 48 and the reducing sleevecenter axis 22. This results in a high concentricity of a reducingsleeve assembly formed in this way.

In addition, the safety unit 48 is provided with a second externalthread 52, by means of which the reducing sleeve 14 can be fastened tothe tool holder 12. The reducing sleeve 14 can thus be screwed into thetool holder 12 via the safety unit 48 so that it is secured againstbeing pulled out of the tool holder 12 along the reducing sleeve centeraxis 22.

The safety unit 48 also has a pull-out safety geometry 54, which isdesigned to form with the machining tool 16 a form fit acting along thereducing sleeve center axis 22.

For this purpose, the pull-out safety geometry 54 engages in anassociated counter geometry 56, which is provided on the tool shaft 18.

In the embodiment shown, the pull-out safety geometry 54 is formed by athreaded section 58, which comprises several bulges or ribs which extendspirally on an inner circumference of the safety unit 48 and form thethreaded section 58.

Accordingly, the counter geometry 56 is formed from several grooveswhich extend spirally on the circumference of the tool shaft 18 and inwhich the bulges or ribs of the threaded section 58 engage.

The machining tool 16 can therefore be screwed to the safety unit 48 viathe pull-out safety geometry 54 and the counter geometry 56 in order tosecure it in a form-fitting manner against being pulled out of thereducing sleeve 14.

In the embodiment shown, the pull-out safety geometry 54 is arrangedradially within the first external thread 50.

A detailed view of the safety unit 48 can be found in FIGS. 12 and 13 .

It can also be seen there that the safety unit 48 has a total of fouroptional axial slots 48 c.

In summary, the reducing sleeve 14, the sealing unit 36, and the safetyunit 48 form a modular system for providing the reducing sleeve assembly13.

The sealing unit 36 or the safety unit 48 or neither of the two isselectively coupled to the reducing sleeve 14 via the multifunctionalinterface 34. Consequently, depending on the machining tool 16 to beused, an appropriate reducing sleeve assembly 13 can always be provided.

Furthermore, the reducing sleeve assembly 13 always provides a centralcoolant supply channel 60 across all of the embodiments described above.Said coolant supply channel can be used to supply coolant to machiningtools 16 which have coolant supply channels.

In the event that the reducing sleeve 14 is used solely for fasteningthe machining tool 16, the central coolant supply channel 60 is formedby an axially open second end 26.

In the event that the sealing unit 36 is used, the central coolantsupply channel is realized by an opening which extends substantiallyaxially and is arranged centrally. The same applies in connection withthe safety unit 48.

As described above, the sealing unit 36 or the safety unit 48 or neitherof the two is selectively coupled to the reducing sleeve 14 by theinternal threads 44 of the multifunctional interface 34. The sealingunit 36 prevents coolant from traveling through all coolant supplychannels 32 provided on the reducing sleeve 14. Alternatively, theO-ring 33 a can be inserted into the coolant supply groove 32 f so thatthe coolant supply slots 32 g are sealed with respect to the coolantsupply on the tool holder side, as shown in FIG. 6 .

FIGS. 14-18 show a reducing sleeve 14 according to another embodiment.In this embodiment, the machining assembly 10 is similar to themachining assembly 10 shown in FIGS. 9 and 10 . However, in theembodiment shown in FIGS. 14-18 , the reducing sleeve 14 does notinclude the O-ring 33 a and the corresponding coolant supply groove 32 fto seal the coolant supply slots 32 g.

Similar to the earlier embodiments, the reducing sleeve 14 shown inFIGS. 14-18 includes the contact flange 28 in the form of acircumferential collar and also serves as an axial stop when thereducing sleeve 14 is inserted into the tool holder 12. In other words,the contact flange 28 is a disc-shaped end section of the reducingsleeve 14, which has an enlarged diameter compared to the body 20.

Also similar to the earlier embodiment, the reducing sleeve shown inFIGS. 14-18 includes at least one coolant supply channel 32. In theillustrated embodiment, the reducing sleeve 14 has a total of fourcoolant supply channels 32. However, it will be appreciated that theinvention is not limited by the number of coolant supply channels 32,and that the invention can be practiced with any desirable number ofcoolant supply channels 32, so long as adequate coolant flow is providedto the machining tool 16.

A portion of the coolant supply channels 28 proximate the second end 24is designed as a groove 33 formed on an outer circumference of the body20. In the illustrated embodiment, two grooves 33 merge into arespective coolant supply channel 32 (i.e., coolant supply grooves 32 eor coolant supply slots 32 g).

A plurality of channel-like outlet nozzles 37 are formed in the contactflange 28 and are in fluid communication with the at least one coolantsupply channel 32. Coolant can be ejected through the outlet nozzles 37onto the machining tool 16 accommodated in the reducing sleeve 14. Itshould be appreciated that the contact flange 28 may include the boresection 32, 32 h instead of the plurality of channel-like outlet nozzles37.

The outlet openings 38 of the outlet nozzles 37 on the end face of thecontact flange 28 can be seen in FIG. 14 . As a result, the number andarrangement of the outlet nozzles 37 can also be seen.

In the exemplary embodiment, there are twelve outlet nozzles 37distributed circumferentially, with the distance between the outletnozzles 37 varying from one another and three outlet nozzles 37 eachbeing assigned to a common coolant supply channel 32.

In FIG. 16 , in particular in the detailed view, it can be seen that alongitudinal axis 40, which runs centrally in the outlet nozzle 36, isinclined in the radial direction relative to the reducing sleeve centralaxis 22, in such a way that the coolant flow exiting from the outletnozzle 36 is directed radially inwards. The inclination in the radialdirection is between about 3° and about 30°. In one embodiment, theinclination in the radial direction is about 8°.

FIG. 18 shows a detailed view of the first end 24 of the reducing sleeve14 on the tool holder side in a perspective view, the walls of thereducing sleeve 14 being shown transparent in order to enable a view ofthe outlet nozzles 37.

It can be seen from FIG. 18 that the longitudinal axes 40 are not onlyinclined in the radial direction, but also in the circumferentialdirection. The inclination in the circumferential direction can also bebetween about 3° and about 30°. In one embodiment, the inclination inthe circumferential direction is about 15°. The inclination in thecircumferential direction is therefore greater than in the radialdirection.

The outlet nozzles 37 are inclined clockwise in the circumferentialdirection in a side view viewed in the direction of the outlet. In otherwords, the outlet nozzles are inclined in the circumferential directioncounter to the centrifugal force that occurs during operation. In theillustrated embodiment, the outlet nozzles 37 are conically shaped andtaper towards the outlet.

As shown in FIG. 18 , each coolant supply channel 32 includes a headersection 52 by which the coolant is distributed to a plurality of outletnozzles 37. In the illustrated embodiment, the header section 52 isassigned three channel-like outlet nozzles 37. However, it will beappreciated that the invention is not limited by the number of outletnozzles 37, and that the invention can be practiced with any desirablenumber of outlet nozzles 37, so long as adequate coolant is provided tothe machining tool 16. In the illustrated embodiment, the header section52 only extends over a partial area of the circumference of the body 20.

FIGS. 19-23 show a safety unit 48 according to another embodiment. Inthis embodiment, the safety unit 48 eliminates the need for the sealingunit 36 for sealing the coolant flow to all the coolant supply channels32 as in the safety unit 48 in the earlier embodiments. Similar to theearlier embodiment, the safety unit 48 includes the second externalthreads 52 for securing the safety unit 48 to the tool holder 12 and thepull-out safety geometry 54. However, the safety unit 48 does notinclude the axial slots 48 c or the first external threads 50 as in theearlier embodiments.

As shown in FIGS. 19-23 , the safety unit 48 includes one or moresegments 62 for mounting a sealing element 64, such as an O-ring, on thesafety unit 48. The O-ring 64 prevents coolant from traveling throughall the coolant supply channels 32 provided on the reducing sleeve 14when mounted on the safety unit 48, similar to the sealing unit 36 andthe O-ring 33 a in the earlier embodiments.

The safety unit 48 also includes a plurality of coolant holes 66extending entirely through a front-end face 65 to the rear-end face 67of the safety unit 48. That is, the coolant holes 66 extend from therear end face 65 to a front-end face 67 of the safety unit 48. Eachcoolant hole 66 is in fluid communication with the at least one coolantsupply channel 32 of the reducing sleeve 14.

As shown in FIG. 24 , coolant is provided to the machining tool 16 onlythrough the central coolant supply channel 60 of the reducing sleeve 14when the O-ring is mounted on the safety unit 48, as indicated by thearrows. A modular reducing sleeve assembly 70 comprises the reducingsleeve 14 and the safety unit 48 as separate parts.

As shown in FIG. 25 , coolant enters at the rear of the safety unit 48,travels through the coolant holes 66, exits between the one or moresegments 62, travels along the coolant supply channels 32 and isprovided to the machining tool 16, as indicated by the arrows, when theO-ring is not mounted on the safety unit 48.

1. A modular reducing sleeve assembly, comprising: a reducing sleevecomprising a reducing sleeve body extending along a reducing sleevecenter axis, the reducing sleeve body having a first end, which is atool-side end in the clamped state of the reducing sleeve, and a secondend opposite to the first end and is a tool holder-side end in theclamped state of the reducing sleeve, the reducing sleeve bodycomprising at least one coolant supply channel extending at a distancefrom the reducing sleeve center axis, the reducing sleeve body furthercomprising a central coolant supply channel; and a safety unit mountedon the second end of the reducing sleeve, the safety unit having apull-out safety geometry and a plurality of coolant holes in fluidcommunication with the at least one coolant supply channel of thereducing sleeve, wherein coolant is directed to a machining tool onlythrough the central coolant supply channel of the safety unit when asealing element is mounted on the safety unit, and wherein coolant isdirected through the plurality of coolant holes of the safety unit andthe at least one coolant supply channel of the reducing sleeve when thesealing element is not mounted on the safety unit.
 2. The modularreducing sleeve according to claim 1, further comprising one or moresegments for mounting the sealing element on the safety unit.
 3. Themodular reducing sleeve assembly according to claim 1, wherein theplurality of coolant holes extends through the safety unit from afront-end face to a rear-end face of the safety unit.
 4. The modularreducing sleeve assembly according to claim 1, wherein the at least onecoolant supply channel extends at least in sections in the interior ofthe reducing sleeve body or at least in sections as a groove thatextends on an outer circumference of the reducing sleeve body.
 5. Themodular reducing sleeve assembly according to claim 1, wherein thereducing sleeve further comprises a plurality of outlet nozzles in fluidcommunication with the at least one coolant supply channel and throughwhich coolant can be ejected onto a machining tool accommodated in themodular reducing sleeve assembly.
 6. The modular reducing sleeveassembly according to claim 5, wherein each nozzle has a longitudinalaxis that is inclined in a radial direction and in a circumferentialdirection with respect to the reducing sleeve center axis.
 7. Themodular reducing sleeve assembly according to claim 6, wherein theinclination in the radial direction and/or in the circumferentialdirection is between about 3° and about 30°.
 8. The modular reducingsleeve assembly according to claim 6, wherein the inclination in thecircumferential direction is greater than in the radial direction. 9.The modular reducing sleeve assembly according to claim 5, wherein theplurality of outlet nozzles are distributed in the circumferentialdirection, the outlet nozzles being inclined differently in the radialdirection and/or in the circumferential direction.
 10. The modularreducing sleeve assembly according to claim 5, wherein each coolantsupply channel includes a header section by which the coolant isdistributed to the plurality of outlet nozzles.
 11. The modular reducingsleeve assembly according to claim 5, wherein at least one outlet nozzletapers towards an outlet.
 12. A machining assembly comprising a toolholder, a reducing sleeve assembly according to claim 1 arranged in thetool holder, and a machining tool with a tool shaft, which isaccommodated in an interior of the reducing sleeve.
 14. The machiningassembly according to claim 13, wherein the reducing sleeve includes asafety unit, and wherein the machining tool is coupled to the safetyunit via a form fit that acts along the reducing sleeve center axis andcounteracts any pulling of the machining tool out of the reducingsleeve.